Microsoft has responded to reports that users of legitimate, registered Windows 10 installations are being told their software is illegitimate while Windows 10 Pro users are being automatically downgraded to Windows 10 Home as a result, claiming that the issue has now been resolved.

Reports began circulating yesterday that Microsoft's Windows 10 operating system was, for some users, issuing warnings that the operating system was not activated and therefore not licensed for use. While Microsoft's approach to software validation means the system could still be used, despite warning messages and a tell-tale watermark being applied to the desktop, the same flaw was blamed for users being automatically downgraded from Windows 10 Pro to Windows 10 Home.

Following the creation of a number of support threads and social media comments, Microsoft has confirmed the flaw and addressed - though without explanation, beyond a separate claim of a 'temporary issue with Microsoft's activation server' - its cause. 'We are aware of reports that some customers' Windows 10 Pro and Windows 10 Enterprise machines are not recognising their licenses as activated.,' explained a Microsoft support staffer of the issue. 'Users may receive the following notification: "Error: you are running Windows 10 Pro, but you have valid digital license for Windows 10 Home," or one of the following error codes: 0X803F8001, 0xC004C003.'

Following investigation into the issue, Microsoft's Jeff Jones issued a statement to press: 'A limited number of customers experienced an activation issue that our engineers have now addressed,' he claimed early this morning. 'Affected customers will see resolution over the next 24 hours as the solution is applied automatically. In the meantime, they can continue to use Windows 10 Pro as usual.'

For those eager to see their licence restored, users affected by the bug have suggested that the Windows 10 Activation Troubleshooter can restore full functionality now the issue with the activation server has been restored.

The activation glitch is the latest in a string of issues affecting Microsoft's operating system, including file-deleting bugs which have seen the Windows 10 October 2018 Update pulled and its re-release delayed seemingly indefinitely - bad news for owners of Nvidia's shiny new GeForce RTX graphics cards, which rely on the DirectX Raytracing functionality included in the October 2018 Update to unlock the full functionality of their new GPUs.